Light signal



A. l- JEROME LIGHT SIGNAL Feb. 6, 1945.

Filed May 1, 1943 INVENTOR AmhzzpLJapome.

film HIS ATTORNEY Patented Feb. 6, 1945 LIGHT SIGNAL Arthur L. Jerome,Edgewood, Pal, assignor to The Union Switch & Signal Company,Swissva1e,.Pa., a corporation of Pennsylvania Application May 1, 1943,Serial No. 485,374

8 Claims. (Cl. 177337) My invention relates to a light signal, andparticularly to a signal capable of selectively projecting a pluralityof beams of light from a single light source. 4 i

More particularly my present invention relates to a Searchlight signalhaving a spectacle arm provided with red, yellow and green filtersadapted to be selectively interposed in the signal beam to cause thesignal to display stop, approach and clear indications.

An object of my invention is to provide novel means for operating thespectacle arm of a signal by two electromagnets so that the spectaclearm may be moved between itsapproach and its clear positions withoutpassing through the stop position.

Another object of the invention is toprovide a signal employing a firstand a second electromagnet which are energized from a polarized controlcircuit in such manner that the first magnet checks operation of thesecond magnet and will not respond unless the second magnet correctlyresponds to the energy supplied over the polarized control circuit.

an improved signal of the type described which is arranged so that thesignal cannot display either its approach or its clear indication unlessthe first electromagnet responds to energy supplied over the controlcircuit to thereby insure that the signal will display its stopindication unless the signal is functioning asintended.

Another object of the invention is to provide a signal of the typedescribed in which the first electromagnet is reversibly connected inseries with the second electromagnet by means of continuity transfercontacts controlled by the second electromagnet so that the supply ofenergy to the second electromagnet is not interrupted during response ofthis magnet to energy supplied over the control circuit.

A further object of the invention is to provide an improved signal ofthe type described which is arranged so that thetwo electromagnets mayboth be energized from one polarized control circuit, or may beseparately energized from different control circuits.

Another object of the invention is to provide improved means forenergizing two electromagnets in series from a polarized controlcircuit.

Other objects of the invention and features of novelty will be apparentfrom the following description taken in connection with the accompanyingdrawing.

According to my invention, a vane or spectacle arm carrying thecolorfilters is biased by a counterweightor other means to one-extremeposition in which a red filter is disposed in the path of the lightbeam, while the'vane is arranged to be moved from this position to theapproach and clear positions by means of a floating lever con-- nectedwith the vane. One end of this floating lever is connected to thearmature of the first electromagnet and the other end ;of this lever isconnected to the armature of the secondelectromagnet. The vane isconnected with the floating 'lever at an intermediate point on the leverwhich is nearer the point of connection of the lever with the armatureof the first electromagnet than the point of connection 'of. the leverwith the armature of the second electromagnet. The various elements ofthe signal are arrangecl so'that when the armature of the firstelectromagnet is released the vane isheld in a position in which a a redfilter is disposedin the path of the light beam irrespective of theposition of the armature of the second electromagnet. The variouselements of the signal j are also'arranged so that when the armature,,of the first electromagnet is picked up the vane is 'moved'totheposition in which'the yellow or the green filter is interposed in thepath of the light beam according as the armature of the secondelectromagnet, is released or picked up.

I shall describe one, form of signal embodying my invention togetherwith a modification .therei of which I may employ, and shall thenpointout the novel features thereof in claims.

v In the drawing Fig. ,l is a diagram of-asignal embodying my invention,and I Fig. 2 is a view of a modification which I may employ. v .7 I IReferring to Fig.1 of the drawing the'signal comprises a vane orspectacle arm In which is supported on a suitable pivot l l, and isprovided with four color filters or roundels. These include a greenfilter G, a yellow filter Y, and twored filters RI and R2, which arearranged to coop:- erate with a lamp l2. In the drawing the lamp i2 isshown above the filters for the purpose of illustration, but it is to beunderstood thatv in actual practice this lamp is located so that thefilters are moved infront of the lamp as the spectacle arm is movedabout the pivot II. In

, addition itis to be understood that the lamp l2 may have associatedtherewith means, not shown,

such as a reflector, for directing through the filter in front of thelamp the rays of light emitted by a the lamp. I

The spectacle arm I0 is connected by a pin M to the upper end of a linkI5, while the lower. end

of the link I5 is connected by a pin I6 to a floating lever [8. One endof the lever I8 is connected by a pin and slot connection IS with thearmature of the first magnet H, while the other end of the lever I8 isconnected by a similar pin and slot connection 20 with the armature ofthe second magnet D.

. The'pin tfiiconnecting the link t5 with the leve I8 is locatedl'atmoisten thelleverilil approximately twice as far from the point ofconnection of the lever IS with the armature of magnet D as it is fromthe point of connection of the lever IS with the armature of the magnetH. The

Various elements of the signal ar'earranged-and proportioned so thatwhen ithe armatures "of the magnets H and D are both released-the:spectacle arm I!) is held in the position in which the red filterRI is located in front ofthelamp l2.

On picking up of the armature of magnetHthe picking up o'ffthearmaturedfthe magnet H, the

spectacle'arm H! "is moved about thepivot H a distance equal to twofilters or roundels. Accordingly, when fthearma'ture of magnetI-rpicksup when 'the-armature' of magnet D is released,

the spectacle arm l-Oj'ijs moved aroundthepivot I far enough tocause'the yellow filter Y'to be 'locatedin'front of-the lamp +2. I

On picking upof the armature of the magnet D'the lever 'l 8 pivots"about the =pin19 associated withthe armature offmagnetfi, while the pinl B islifted a distance substantially equal to 'onethirdof *thedistance'that'the"pin 20 associated with thelmagn'et D is lifted. Thevarious "elejments'o'f the signal are proportioned so that on'pickingup'ofthe armature of magnet'D the specta'cle'arm'ismoved aboutthe pivot H a distance equal'to'one filter or'roundel; Accordingly, whenthe armature "ofmagnet D picks up *when the armature of magnet H ispicked up the spectacle arm "is moved from the position in which theyellow filter Y is "located "in front'of lamp H to "the,positioninWhiCh"the green filter G is located in front of the. lamp 12, whilewhen the armature ofmagnet Dpicks'up'whenth'e armatureof maghand to itsright-hand terminal. The construction of the magnet D is not a part ofthis inven- 'tionand thismagnet may be constructed in any appropriatemanner Well-known in the art. One

form of construction which may be employed is shownin-LetterszPatent ofthe United States No.

2303,4388; iss'uedflune 11, 1940, to H. E. Ashworth.

The windings of the magnets D and H are energized from a polarizedcontrol circuit over a circuit similar to that shown and claimed inapplication for Letters Patent of the United States, se n i'a'lf-tlo.124,1151,"of A. Dodd. This circuit "includes make-before-break contacts"which 'are operated o me armature of the magnet D.

Eitherfor both 'o'f the magnets D and H may have contacts operated bythe "armature of the magnetasshown in the drawing, andtheseco'ntacts may'be employed inany appropriate manner; I

Energy is supplied from a source'of'direct current, the terminals ofwhich are designated I and to the windings off-the magnets D and'H.

net H -isreleaseol. the spectacle arm is moved from the position inWhichthefilter'Rl is located in front of 'lamp "F2 to the position'inwhich filter R2 is located in frontoflampf-Z. I

In the drawing, the armatures of "the magnets are shown in theirreleased positions, while the picked up pos'itionswof these armatures'are indicated by broken lines. In addition, broken lines extend betweenthe ends of the armatures 'in their picked up'and released positions toillus- "trate'theefiect of'movement of the armatures on 'the- 'pin F6,and therefore onthe spectacle arm l0.

For convenience, each position of the-pin I6 is designated'by thereference character ofthe'filter which is 'located'in front of the lamp12 in that position of the pm. When the armatures of both magnetsarereleasedfthe'pin It occupies its low 'ermostposition R1 in Wh iCh'fthered filter BI is I located in "front of the'lamp [-2. When the' arms;-

ture'of magnet D' is picked up and the armature 7' "of magnet H isreleased the pm It is lifted one The polarity of the energy suppliedfrom the 'source'is governed by'contactsHand 2'4 ofa pole changer PCwhich may be governed by any appropriate condition, as for example,trafiic'conditionsln-advance of the signal. The supply of energy to't'hecontrol'wires'is governed by "a 'contact 2'5 which-maybe contro'lledinany desired 'manner; I

'The' equipment is shown in the condition which itassumes'when contact25"is released so that the supply of 'energy'tothe windings of themagnets D and H is interrupted. As the windings ofthe 'magne'ts'D and Eare not energized the armatures of these magnets are moved by gravityorothermeans to "their lowerflpositionsjas shown so'that force isexerted through the-floating lever 1'8 and-the link I5 tocausethespe'cta'cle arm It to occupy the position in which the redfilter Rl is located in front ofth'e lamp 12. Accordingly; the signalprovides its red 'or stop indication. I I

' -'On picking up of "contact 25 when the pole changingcontact '23 and 23" are released energ of reverse 'polarity'is supplied to the controlwires and flows through 'the'windin'gs of the magnets D and Hover thecircuit which is traced from the "positive terminal of the source overcontact D -from right to left, wire '30, and back contact '23 to thenegative terminal of the source.

The direction of 'flowof energy through the winding of magnet 'D'is suchthat the armature of this magnet will not pick up, but remains released,so contacts 28 'and2 9 maintain thecircuit traced above. The energysupplied through the winding of magnet'H causes the armature of thismagnet to pick up and thereby lift the righthandend of the floatinglever [8 so that force I is exertedthrough the lever 18, and the link Itto move the spectacle arm about the pivotll' to the-position in whichthe yellow filter Y is 10- cated in front of the lamp [2. Accordingly,the signal now provides its yellow or'caution indication. 7

If the contacts 23' and 24 are now picked up,

the energy suppliedcto the control wires 21 and 30 is changed fromreverse to normal polarity.

On the supply of energy of normal polarity to the wires 21 and 30,energy flows from the posi- When contact 32 engages contact 29 a circuitA is established to connect the winding of magnet D across the controlwires 21 and'30 in series with the winding of magnet 1-1. ,This circuitis I traced from the right-hand terminalof the wind ing of magnet D overcontacts. 29 and 32, winding of magnet H from left to right, and throughasymmetric unit K2 to wire 21. 7

It will be seen, therefore, that on the supply of energy of normalpolarity to the control wires 21 and 30 energy is supplied to thewinding of magnet D over the circuit controlled by, contacts 29 and 28,While on picking up of the armaturev of the magnet contact 32 engagescontact 29 to establish the circuit for energizing the winding of magnetD in series with the winding of magnet H before contact 29 is moved outof engagement with contact 28. Accordingly, there is no inter? ruptionin the upply of energy to the winding of magnet D and the armature ofthis magnet is certain to complete its movement to its picked upposition.

On the change in the energy supplied to the control wires from reverseto normal'polarity the supply of energy to the winding of magnet H isinterrupted until the armature of magnet D picks up. However, during theperiod in which i the supply of energy to the winding of magnet H isinterrupted the asymmetric units KI and K2 provide a snubbing circuitfor the winding of magnet H to thereby render the magnet slow to releasewith the result that the armature remains picked up during the period inwhich the supply of energ to the winding of the magnet is interrupted.After the armature of magnet D picks up the windings of magnets D and Hare energized in series'and the armatures of both of both magnets arepicked up, contact 1 5 opened to cut off the supply of energy to themagnets D and H, the armatures of both magnet will release, while thespectacle arm It will be returned to the position in which it is shownin which the red filter RI is'located in front of the lamp I2. If whileenergy of normal polarity is supplied to the control wires 21 and andthe armatures ofthelamp l2.

of the magnets D and H are both picked up, the contacts 23 and 24 arereleased to change the energy supplied to wires 21 and 30 from normal toreverse polarity, the 'supplyof 1 energy to the windings of magnets Dand H in series will be interrupted, while energy will be supplied tothe winding of magnet D over the circuit traced from the positiveterminal of the source over contact 25, back contact 24, wire 21,asymmetric unit Kl, contact 32 and 29, winding of magnet D from right toleft, wire 30,,and back contact. 23 to the negative terminal of thesource. Energy flowing through ,the winding of magnet D from right toleft reverses the fiux in the core of the magnet with the result thatthe armature of the magnet releases and thereafter remains released.

On movement of the armature of this magnet to its released positioncontact 32 is moved out of engagement with contact 29 to therebyinterrupt the circuit just traced for energizing the winding of magnet Dthrough the asymmetric unit Kl, while contact 29 is moved into.engagement with contact 28 to establish a circuit for energizing themagnet D in series'withthe winding of magnet H. This circuit is tracedfrom the wire 21 through asyrmnetric unit Kl, winding of magnet H fromleft to right, contacts 28 and 29, and winding of magnet D from right toleft to wire 30. Accordingly, energy continues to flow through thewinding of magnet D-from right to left so the armature of this magnetremains released while energy isagain supplied through the winding'ofmagnet H from left to right to keep the armature of this magnet pickedup. The winding of magnet H is snubbed by the circuit through theasymmetric units KI andKz during the period .in which the supply ofenergy to the winding is interrupted so that the armature of the magnetremains picked up until energy is again supplied to the, magnet winding.

On release of the armature of the magnet D while the armature of magnetH is picked up the left-hand end of the lever I8 is lowered so force istransmitted through the lever l8 and, the link l5 to move the spectaclearm It to the position in which the yellow filter Y is located in frontIf, while energy of reverse polarity is being supplied to wires 21 and30 and the armature of magnet H is picked up to cause the signal todisplay its yellow or caution indication, the contact 25 is opened, thearmature of magnet H will releaseand the spectacle arm II) will be movedto theposition in which red filter RI is located in front of the lampl2. 1 v

This signal is arranged sothat if the armature of the magnet D picks upon the supply of energy of reverse polarity to the control wires 21 and30 the signal will display it red or stop indication.

On the supply of energy of reverse polarity to the control wires whenthe armature of magnet D is released, energy flows from the positiveterminal of the source over contact 25, back contact 24, wire 21,asymmetric unit Kl; winding of magnet H, contacts 28 and '29, windin ofmagnet D from right to left, and back contact 23 to the negativeterminal of the source. On flow of energy through the winding of magnetD from right to left, thearmature of this magnet should not pick up, butif for any reason the armature does pick up and thereafter remains;picked up, the circuit just traced for energizing the windings ofmagnets D and H in series will be interrupted because of disengagementof contact 29 from concontrol wires.

21 through asymmetric unit Kl, contacts '32 and tact '28, and a circuitwill be established to connect the winding of magnet D directlyaerossthe This circuit is traced from wire 29, and winding of magnet .D fromright to left, to wire 30. i

The energ-y'supplied to the winding :of magnet D may maintain .thearmature of the magnet picked up, but as long as the armature remainspicked up the winding of magnet His shunted by asymmetric unit K1 andits-armature releases and remains released..- When the armatureuofmagnet D is picked up and the armature of magnet H is released, theleft-hand :end of the lever I8 is lifted and force is exerted throughthe lever I8 and the link 15 to move the spectacle arm in to theposition in which the red filter R2 is lo-.

cated in front of the lamp 12. Accordingly, when the armature of magnetD is improperlypicked up, the armature of magnet H is released and thesignal operates to provide a red or stop indication. I I 4 When energyof reverse polarity is supplied to the control wires 21 and 3ll'tharmature of the magnet D will normally be released and the armaa ch'eckon operation of magnet D and the armature ofmagnet H will be released ifthe armature of magnet D is picked up at a time where energy of reversepolarity is supplied to the control wires. When the armature of magnet His released the signal displays ared or stop indication regardless ofthe position of the armature of'the-magnet D. The operation of thesignal, therefore, is such as to provide the maximum degree of safetysince the signal will provide its stop indication unless the signalis'function-ing to provide the proper indication.

As pointed 'out above, on a change in the polarity of the energysupplied to the control wires 21 and 313, whether this change is fromnormal to reverse polarity or from reverse to normal polarity, thesupply of energy to the winding of magnet H is interrupted untilthearmature of magnet D moves to a position in correspondence with thepolarity of the energy supplied to the winding of the device. Oninterruption of the supply of energy to the winding of magnet H armatureof this magnet is maintained picked up for a short period because of thesnubbing circuit which exists for the magnet winding through theasymmetric units KI and K2. This snubbing circuit for the magnet Hserves to maintain the armature of the magnet picked up for a periodlong enough to enable the armature of the magnet D to respond to achange'in the polarity of the energy supplied to the winding of magnetD. Since the armature of magnet H ismaintained picked. up on a change inthe polarity of the energy supplied to the control wires, the, spectaclearm i is moved between the yellow and "green ositions without moving tothe red position as would occur if the armature of the magnet Hshouldrelease. The operation of the signal, therefore, is such thatchanges between the yellow and green indications occur without momentaryflashes of the red indication.

' armature of the second electromagnet is in its first a'eesyree "Whilethe spectacle arm has been illustrated and described as being providedwith two separate red filters, it is obvious that one filter largeenough to extend'in front {of the lamp I2 in two positions of thespectacle arm, asshownin Fig. 2, might be employed instead.

Although I have herein shown and described only one form of signalembodying my invention, it is understood that various changes andmodifications maybemade therein within the. scope of 'the appendedclaims without departing from the spirit and scope of. my invention.

I Having thus described my invention, what I claim is: v

1: In a light signal, in combination, a spectacle arm carrying a firstand a second red filter, a yellow and a green filterwhic'h are adaptedto be interposed in a beam 'of light-to cause the signal to provide'red,yellow and green indications, a first and a second electromagnet eachhaving an armature movable between afirst and a second position, andmeans for operating saidspectacl'e arm by the armatures of saidelectromagn'et in such manner that when the armature of the firstelectromagnet is 'in i'ts'first position the first or the second redfilter is interposed in the light beam according as the armature of thesecond electromagnet is in its first or its second position and so thatwhen the armature of the first electromagne't is in its secondpositionthe yellow or the green filter is interposed in the light beam accordingas the armature of the second electro magnet is in its first or itssecond position.'

2. In a light signal, in combination, a spectacle arm carrying aplurality of difierent filters which are adapted'to be interposedinabe'am of light to cause the signal to'provide a plurality ofdifferentindications, said filters including a red and a green filterand a yellow filter disposed between said red and green filters tothereby permit the spectacle arm to be moved between the positions inwhich thegreen and yellow filters are interposed in the light beamwithout passing through the position in which a red filteris interposedin the light beam, a first electromagnet having an armature biased to areleased position, a second electromagnet having an armature which ismoved from a first to a, second position when and only when energyflowsthrough the winding of the electromagnet in a particular clirection, apair of control :wires, ,means for at times supplying energy of onepolarity and at other times supplying energy of the other polarity tosaid control wires, means including a contact governed by the armatureof said second electromagnet for'reversibly connecting the winding ofsaid first electromagnet across said control wires in series with thewinding of said second electromagnet, and means for operating saidspectacle arm by the armatures of said electromagnets in such mannerthat when the armature of the first electromagnet is released a redfilter is inter} posed in the light beam regardless of the position ofthe armature of the second electromagnet and so that when the armatureof the first" electromagnet is picked up the yellow or the green'filte'ris'interposed in the light beam according as the or its second position.3. In a light signal, in combination, a spectacle arm carrying aplurality of different filters which are adapted to be interposed in abeam of light to cause the signal to providea plurality of differentindications, said filters including a red and 'a green filter and ayellow filter disposed between said red and green filters to therebypermit the spectacle arm to be moved between the positions in which thegreen and yellow filters are interposed inthe light beam without passingthrough the position in which a red filter is interposed in the lightbeam, a first electromagnet having an armature biased toareleasedposition, a second electromagnet having an armature which is moved froma first to a second position when and only when energy flows through thewinding of the electromagnet in a particular direction, a pair ofcontrol wires, means for at times supplying energy of one polarity andat other times supplying energy of the other polarity to said controlwires, means including make-before-break contacts governed by thearmature of said second electromagnet for reversibly connecting thewinding of said first electromagnet across said control wires inserieswith the winding of said second electromagnet, and means foroperating said spectacle arm by the armatures of said electromagnets insuch manner that when the armature of the first electromagnet isreleased a red filter is interposed in the light beam regardless of theposition of the armature of the second electromagnet and so that whenthe armature of the first electromagnet is picked up the yellow or thegreen filter is interposed in the light beam according'as the armatureof the second electromagnet is in its first or its second position.

4. In a. light signal, in combination, a spectacle arm carrying aplurality of difierent filters which are adapted to be interposed in abeam of light to cause the signal to provide a plurality'of differentmeans for operating said spectacle arm by the armatures or saidlectromagnets in such manner that when the armature oi':the firstelectromagnet is released a red filter is'interposed in the light beamregardless of the position of the armature of said second electromagnetand so that when the armature of said firstelectromagnet is pickedup theyellowor the green filter is interposed in the light beam according asthe armature of the second electromagnet is in its first or its secondposition.

5. In a light signal, in combination, a spectacle arm carrying aplurality of difierent filters which are adapted to be interposed in abeam of'light to cause the signal to provide a plurality of differentindications, said filters includinga red and a green filter and a.yellow filter vdisposed between said red and green filters to therebypermit the spectacle arm to be moved between the positions in which thegreen and yellow filtersare interposed in the light beam without passingthrough the position in which a red filter is interposed in the lightbeam, 3.

first and a second control conductorto which energy of normal polarityis supplied at times and to which energy of reverse polarityis suppliedat other times, a first electromagnet having an armature biased toa,released position and movable therefrom to a picked up posi-' tion,asecond electromagnet having its winding connected .in series with oneof said conductors and having an armature movable between a positionwhen and only when energy flows ductor to which energy or normalpolarity is supplied at times and to which energy of reverse polarity issupplied at other times, a first electromagnet having an armature biasedto a released position and movable therefrom to a picked up position, asecond electromagnet having its wind-, ing connected in series with oneof said conductors and having an armature movable between a. first and asecond position, said second electromagnet being of a type the armatureof which when in its first position is moved to its second position whenand only when energy flows through the Winding of said electromagnetfrom said first to said second conductor, means includingmake-beforebreak contacts governed by the armature of said secondelectromagnet and effective when said armature is released to connectsaid conductors together through an asymmetric unit poled to permitenergy to flow from the second to the first conductor and to alsoconnect said conductors together through the winding of said firstelectromagnet with the first conductor connected to a selected terminalof the winding of said first electromagnet and being-efiective when thearmature of said second electromagnet is in its second position toconnect said conductors together through an asymmetric unit poled topermit energy to flow through the winding of said electromagnet fromsaidcfirst to saidsecond conductor, means including make-before-breakcontacts governed by the armature of said second electromagnet andeffective when said armature is released to connect said conductorstogether through an asymmetric unit poled to permit energy to fiow fromthe second to the first conductor and to also "connect saidconductorstogether through the winding of said first electromagnet with the firstconductor connected to a selected termi-' nal of the winding of saidfirst electromagnet andbeing efiective when the armature of saidsecondlelectromagnet is in its second position to connect saidconductors together through an asymmetric unit poled to permit energy to110W from'the first to the second conductor and to also connect saidconductors together through thewinding ofthe first electromagnet withthe second conductor connected to said selected terminalof the windingof said first electromagnet, and means for operating said spectacle armby the armatures of said electromagnets so that when the armature of thefirst electromagnet is released and the armature of the secondelectromagnet is in its first position, the

from the first to the second conductor and to also connect saidconductors together through the winding of the first electromagnet withthe second conductor connected to said selected terminal of the windingof said first electromagnet, and

,rality of difierent indications, said filters including a red and agreen filter and a yellow filter disposed between said red and greenfilters to thereby' permitth'e spectacle armto': be moved betweenthepositions-in; which the green: and yellow filtersare interposedinthelight beam without passing through the". position in which a redfilteris interposed in the light beam, :1. first and a second controlconductor to which energy of normal polarity is supplied at times andto. which energy of reverse polarity is supplied. at other times afirstelectromagnet having an armature biased to.a..released position andmovable therefrom to a picked up position, a second electromagnet havingits. winding connected in series with one of said conductors and havingan armature movable between afirst and asecond position, said secondelectromagnet being. of a type thearmature of which when in its firstposition is moved to its second position when and: only. :whenenergyflows through the winding of said electromagnetfrom said first to saidsecond. conductor, an asymmetric unit said armature .is .in its.firstorits second posi:

tion to connect theother control conductor to the first or thesecondterminalof said. asymmetric 'a-gecerzea electromagnet andijfsupportediat a second point by the armature of: the second electnomag net, ."andmeans: connected. with, saida lever: for

moving said: spectacle: arm, saidamean's being, ar range-dso that whenthe-armatureof. the: first electromagnet is in its: firstpositionmovement of thearmatureof. the second electromagnet I betweenits two positions causes the spectacle arm t'obe moved between theposition in which the first red filteris interposed in; the, light beam.and the position which the second red filter .isi nterpos'edin the;light beam" and also being arranged so that; when/[the armature of; thefirst electromagnet is; in itsgsecond' position movement oftho;armature: of the second electromaghet from itsfirst togits secondposition causes the spectacle arm to be moved from the: positioninwhichthe yellow filter: is'i-nterr posed the light beamto' the position inwhich the green. filter isinterposedginrthe light beam.

8'. Ina light signalin. combination, a,,fi-rst and a secondelectrcmagnet each having an armature biasedv to a released positionand; movable therefrom to a piokedup position, a floating leversupported at a firstp'ointby the armature of the first electromagnetand; supported at a second point by the armature of the secondelectrom-agnet, a spectacle arm biased to a posi-tio-n in which'itcausesthe signal to provide a stopindication and movable therefrom. through acaution position inwhich it causesthe signal unit,;and meansforoperating; said spectacle arm manner that aredfilter-is interposed inthe light beam when, the-armature of said first electro magnet .is'.released regardlessof'the position of the armature of the secondelectromagnet and by the armatures. of said electromagnets insuch sothatwhen the armature of the first electro.:

magnet is picked up theyellow .or .thexgreen filter is interposed thelightjbeam according as the armature of the second ,electromagnet is inits firstor. itsv secondpositiom '7..,In a light signal, in combination,a spectacle arm carrying a first and a second red filter, a yellow and agreen filter which are adapted .to. be interposed. in a. beam of lighttoicause the.

' signal to provide. red, yellow and green indications, a first and asecond electromagneteach having an armature movable between a firstand asecond position, a floatingv lever. supported at a first point by the.armature of the first to, provide a caution indication. to aclearposition in which it causes" the signal toprovide a clearindication, saidspec-tacle arm:- beingoperatively connectedwith saidlever in such'manner that when the armaturesofboth of saide1ectromagnets are released the spectacle armoccupies its ,stopposition, the point of connection of the spectacle arm with said lever,the amount of movement of the leverby the armatures of saidelectromagnets and the distance between the different positionsof thespectacle arm being arranged and proportioned so that picking up of thearmature of thefirst electromagnet will move the spectacle arm from thestop to the caution position and so that picking up of the armaturebfthe second eleotromagnet will not move-the spectacle arm from the stopto the caution position if the armatureof the first electromagnetisreleased but will move the spectacle arm f rom the caution to the clearposition if the armature of the first electromagnet is picked p I v H 1i

